Using a Piezoelectric Actuator for Precision Motion Control

When it comes to precision motion control, very few actuator types can match the exactness of piezoelectric actuators. This has naturally made these actuators the preferred actuation solution in a myriad of applications. This article elucidates on the several desirable attributes demonstrated by piezoelectric positioning systems.

These actuators have been commercially available for 35 years, and have continuously adapted and evolved during this period. Quartz, barium titanate, lead niobate, and lead zirconate titanate are some examples of piezoelectric materials. The two major properties of piezoelectric materials are:

  • They produce an electric voltage when pressure is applied to them.
  • They mechanically deform in response to an applied electric charge/voltage.

The entire range of piezoelectric actuators is built on these basic principles. The use of these actuators spans across various industrial, commercial, and consumer applications. Here are some key properties of piezoelectric actuators that make them the preferred choice in precision motion control:

  • Infinite resolution: Piezoelectric actuators don’t comprise moving parts, as they directly convert electrical energy into mechanical energy, and vice versa. The absence of moving parts enables unlimited resolution.
  • Responsive actuation: Such actuators are highly responsive, and react to electric exposure in a few microseconds or less. These actuators can even provide acceleration rates up to 10,000 g and even more.
  • Ability to generate high force: With the evolution of piezoelectric actuators, it is now possible to move loads of several tons. Even with these loads, the linear motor/actuator can control travel ranges of up to 100 micrometers with sub-nanometer resolutions.
  • No magnetic interference: Certain applications have zero tolerance to magnetic fields. Piezoelectric actuators are best suited for such applications because the piezoelectric effect is primarily related to electric fields. Such a linear motor/actuator is not affected by magnetic fields. They also do not produce magnetic fields of their own.
  • Energy efficiency: Even when these actuators are required to hold heavy loads for a very long time, they do not demonstrate a significant energy loss. Static operation thus becomes surprisingly energy and cost-efficient. Simply stated, these actuators are capable of storing energy just like an electrical capacitor.

In addition to the features mentioned above, piezoelectric actuators are also capable of functioning normally in vacuum environments where quality precision motion control is required. And, they are compatible for use in clean room applications as they do not require the use of lubricants. Additionally, if your application requires an actuator that can function at cryogenic temperatures, you can request your manufacturer to create a special actuator suited to such environments.

Given these characteristics, piezoelectric actuators are increasingly preferred for precision motion control in data storage, semiconductors, life science and medical technology, precision mechanics, optics, photonics, and so on.

How Precision Machining Is Used In The Shipping Industry

The shipping industry is one of the most important in the entire world. Without the ability to transport large quantities of goods around the world, whole countries could collapse. In this article we will look at what part precision machining plays in this vital, global industry.

Precision machining in the ports

Precision made parts are essential in the loading and unloading of huge container ships. As containers grow in size and weight, cranes must also grow in size to be able to deal with the increase in demand. Central to this is the technology used in the crane’s winch. Here, CNC machined parts are essential to ensure winches can be constructed to high operational tolerances, with the torque and horsepower required to lift vast weights.

To make winches stronger, precision machining is used to ensure that the electric motors that power the winch have the durability to be put under immense loads around the clock, with minimal maintenance required. It would be unacceptable for a winch in a port to require regular maintenance, as this would mean there would be a delay in loading or unloading ships. Winches in cranes at ports therefore use precision parts made to high tolerance levels which are designed specifically to need as little servicing as possible.

Uses On Container Ships

Every ship sailing currently uses parts made using precision machining methods. Most commonly, these parts are found in the engine bay. A recent trend employed by shipping firms as a way to reduce fuel consumption across their fleet is to use ‘slow steaming’. This is when ships sale as slow as 15 knots, rather than the usual 20 to 30 knots, in an effort to reduce fuel consumption. Unfortunately, while a sound theory, typical ship’s engines are designed to be most powerful and efficient at maximum power. This is because the average ship designed twenty or thirty years ago was never expected to travel lower than maximum speed, other than when docking. The effect of slow steaming as a result is lower fuel consumption at the expense of higher maintenance costs, because the components in the engine were not designed to operate at slower speeds.

The solution is to replace engine components including cam shafts, pistons and push rods with redesigned parts, crafted using precision machining. These parts are designed on computers and made with CNC engineering and are specifically designed to tolerate the different frequency of vibrations and levels of engine wear found when engines are running at a lower RPM (revolutions per minute). In addition to these revised parts, the engine management system can be tuned to improve fuel consumption and torque at lower speeds, much like a car tuner would do in their garage. Finally, the gearing of the engine can be changed with a revised gearbox that optimises the rotation of the ship’s screws in relation to the engine’s speed, meaning less energy is wasted and more energy is used to push the ship forward. The result is that CNC machining actually helps reduce shipping costs, and therefore lower prices for end consumers like us.

Try Miniature Translation Stage for Precision Positioning

Today, a number of applications that require highly measured and control motion over a few millimeters rely on micropositioning systems to achieve the desired results. Micropositioning systems essentially comprise of stages that are driven by a motor and are capable of covering travel ranges ranging from a couple of millimeters to several hundred millimeters. Such systems also possesses a resolution and repeatability that up to 1 micron. However, it needs to be noted here that these two factors are limited mainly because the guiding systems tend to produce a small amount of friction.

A miniature translation stage can be employed in order to achieve precision positioning. These devices are intelligently engineered and have several desirable features. Leading companies offer models that feature add-ons such as an optical linear encoder and an efficient ball screw. Let’s take a look at some of the other features that prove to be the USP of these micropositioners.

  • You can expect to achieve a travel range of 25mm, which is great for smaller devices that require highly precise distances. These devices are usually palm-top-sized.
  • The presence of a 0.1 micron optical linear encoder allows the user to benefit from a higher accuracy and repeatability. And with a minimum incremental motion of just about 0.2 microns, the positioning is precise.
  • You could use these devices for applications that require a velocity of up to 20 millimeters per second.
  • The presence of cross roller bearings helps bring down the occurrence of friction to the minimum possible level. The same features help in reducing backlash to a considerable extent. Experts opine that the efficiency of these devices is much better than lead screws.
  • Overall, such devices require comparatively low investments in maintenance and a markedly better duty-cycle operation, even at velocities that go up to 20 millimeters per second.
  • These precision positioning machines also feature re-circulating ball screw drives because of which the users can expect higher speeds and longer lifetimes.
  • Some of the most commonly known application areas of these devices is in photonics packaging, fiber positioning, metrology, testing equipment, micromachining and even quality assurance testing.

It is wise to invest in these precision positioning devices because they offer several operational advantages over and above the conventionally used stepper motor stages. In fact, they are also a better alternative to rotary encoder servo motor stages. In comparison with conventionally used devices, you can expect these new age micropositioners to incur a lower maintenance costs, thus translating into a lower ownership cost. All in all, if you are looking for higher performance at the most marginal costs, you could consider investing in the new age miniature translation stages for precision positioning.